Toward Extremely Fast Charging through Boosting Intercalative Redox Pseudocapacitance: A SbCrSe3 Anode for Large and Fast Sodium Storage

Abstract Alloying‐type metals with high theoretical capacity are promising anode materials for sodium ion batteries, but suffer from large volume expansion and sluggish reaction kinetics. Dispersing alloying‐type metal into a buffer matrix with interfacial anionic covalent bonding is an effective method to solve the above issues. Here, this bifunctional structural unit is designed by incorporating high‐capacity Sb metal into a rigid CrSe framework for fast‐charging applications. The high‐capacity and high‐rate sodium storage can be synergistically realized in the bifunctional SbCrSe system, where the rigid CrSe framework endows the SbCrSe 3 anodes with superior structural stability and improved intercalative redox pseudocapacitance. Moreover, the volume expansion of Sb during discharge can be buffered by the CrSe chain‐like matrix. The novel SbCrSe 3 anode delivers a high charge capacity of 472 mAh g −1 at a current density of 0.4 C and retains ≈100% capacity at 60 C over 10 000 cycles. Further in situ and ex situ characterization reveal the multistep reaction mechanism, and the breakage and formation of reversible SbSe bonds during (dis)charge. The proposed bifunctional structural unit that combines alloying type anodes and intercalative anodes is expected to pave a new road for the development of high capacity and high rate anode materials.